Research Projects

Cancer biomarker detection at low concentrations requires highly sensitive, label-free, and non-destructive sensors that enable remote sensing, multiplexing, and simple integration with current microfluidic systems. Photonic microcavity-based sensors typically use an evanescent field coupling approach, which is sensitive to vibrational disturbances and cumbersome. Quantum dots or fluorescent dyes have been incorporated into dielectric or polymer microspheres to exhibit WGM sensing, reducing the micrometer-scale size of the sensing platform. However, these microresonators have limitations such as low Q-factor, uneven doping, photobleaching, and complicated doping methods. This study presents a photonic microcavity sensor based on WGM of ZnO microspheres for ultrasensitive prostate cancer detection using prostate-specific antigen (PSA). ZnO exhibits intense luminescence, is low toxicity, and has a spherical geometry that permits optical cavity modes (WGMs). ZnO microspheres can be easily prepared using a straightforward one-pot hydrothermal synthesis from inexpensive starting materials, without the need for complex coupling schemes or costly light sources. By measuring mode strength and WGM shifts induced by binding prostate cancer biomarkers to the ZnO surface, the presence of prostate cancer can be identified. ZnO microspheres can be easily incorporated with existing microfluidic systems, enabling miniaturized label-free multiplex optical sensing. This is the first attempt to construct a photonic microcavity sensor using WGM of a ZnO microsphere to detect prostate cancer in the Indian context.